An Ultralow-Profile Dual Circularly Polarized Beam-Scanning Array Antenna Based on Risley Prism at L-Band

An innovative ultra-low-profile dual circularly polarization (DCP) beam-reconfigurable array antenna based on the Risley Prism beam-scanning principle (RPSP), operating in the L-band, is proposed in this communication. An upgraded version of RPSP combines a large-aperture feed array antenna and a phase-gradient transmissive metasurface (TM), both featuring linear gradient phase (LGP) properties, to achieve the ultra-low profile characteristics. Additionally, a passive DCP transmissive metasurface operating in the L-band is designed for the first time, offering 360° phase control and high transmission efficiency. The large array feed antenna is implemented using an 8×8 array of stacked microstrip patches, achieving DCP radiation based on 3 dB couplers. By mechanically rotating the two array layers, the beam can achieve elevation angle scanning from 0° to 48° and azimuth angle scanning from 0° to 360° for DCP radiation. The measured maximum aperture efficiency (AE) reaches 37.63% at 1.65 GHz, with the antenna profile height being 77 mm (0.41λ0). The proposed DCP-RPA features an ultra-low profile, low-cost manufacturability, and low loss, making it highly suitable for applications in weather radar, satellite communications, and next-generation mobile communication.